AU673956B2

AU673956B2 - Shaft coupling

Info

Publication number: AU673956B2
Application number: AU77054/94A
Authority: AU
Inventors: Laurence George Barton
Original assignee: Torrington Co Ltd; Torrington Co
Current assignee: Torrington Co Ltd
Priority date: 1993-10-04
Filing date: 1994-09-30
Publication date: 1996-11-28
Anticipated expiration: 2014-09-30
Also published as: CN1132492A; DE69403345D1; WO1995009757A1; EP0721411B1; GB2282433A; DE69403345T2; US5653146A; JPH09503183A; CA2171309A1; BR9407745A; AU7705494A; EP0721411A1; GB9320388D0

Description

I

SHAFT COUPLING This invention relates to a shaft coupling and more particularly to shaft couplings for vehicle steering columns.

Hitherto, with rotatable shaft couplings, e.g. for use in vehicle steering columns, there has been a problem of how to obtain satisfactory torque transmission through the coupling if the two ends of the shaft are mounted at an angle to one another.

Furthermore, it is desirable for the coupling to allow collapse of the two ends of the shaft towards one another in the event of a vehicle crash.

According to one aspect of the present invention, there is provided a shaft coupling comprising two universal joints and a torque transmitting means for pivotally connecting the two universal joints and for transmitting torque from one universal joint to the other universal joint, characterised in that the torque transmitting means includes a single central pivot pin, through which torque from one universal joint is transmitted to the other universal joint.

AMENDED SHEET la The invention also extends to a vehicle steering column incorporating a shaft coupling essentially as just defined.

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,ti' rr' SHE-T I I WO 95/09757 PCT/GB94/02136 2 For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which:- Figure 1 shows an adjustable vehicle steering column incorporating a shaft coupling; Figure 2 is a perspective view of the ohaft coupling shown in Figure 1 with the shaft coupling in an open position; Figure 3 is a perspective view of the shaft coupling shown in Figure 1 with the shaft coupling in a collapsed position; and Figure 4 is a cross-sectional view taken on line 8-8 of Figure 2, showing the details of the central pivot pin and rubber bush.

Referring to Figure 1, the adjustable steering column assembly 15 includes a steering rack 20, a lower, fixed mounting point 21, a lower shaft 23 of the steering column, a steering wheel and an upper fixed mounting point 6 for the steering column assembly 15. The lower shaft 23 and steering rack 20 are connected a shaft coupling 10 of the present invention.

Steering column assembly 15 is reach ani/or rake adjustable as shown by arrows A and B. An adjustment mechanism 27 is provided to reach adjust and/or rake adjust steering column assembly The coupling includes two yokes, 1, 2, into which are to be mounted the ends of the shaft 23 and steering rack 20 pinion shaft. Figure 2 shows the coupling 10 in a normal operating, open position. The end of the steering rack 20 pinion shaft WO 95/09757 PCT/GB94/02136 3is mounted in an aperture 1A of the yoke 1 and the end of the lower shaft 23 is mounted in an aperture 2A of the yoke 2.

The yokes 1 and 2 are linked by cross members 4A, 4B, fitted in apertures 1B, 2B, iespectively, in the limbs of the yokes, to an elbow member 3.

The elbow member 3 comprises two forked limbs 3A, 3B pivotably mounted together at 3C on a central pivot pin 5. Respective outer ends of the limbs 3A, 3B, i.e. the forked ends, are mounted on pivot points of the respective cross members 4A, 4B at 3D, 3E, on which the yokes 1 and 2 are also mounted.

It will be noted that the pivot axes 7A, 7B of the respective crosses 4A, 4B on the elbow member 3 are parallel to one another and are also parallel to the common pivot axis 8 of the two limbs 3A, 3B of the elbow member 3.

However, in the event of a vehicle crash, one limb, for example the limb 3A, can be pushed oy the steering rack pinion shaft to pivot so far that the limb 3A will close in on the edge walls of the fork of the limb 3B in the direction of the arrow C. In this condition, crash effort can be transmitted through the shaft coupling to a vehicle crash impact energy absorbing mechanism (not shown). The coupling 10 allows thie collapse effort to work through the coupling whatever the angle of mounting of the lower shaft 23 and the steering rack 20 pinion shaft of the vehicle steering column.

A vibration inhibiting isolator can be provided in the coupling 10 and one way of achieving this is by bonding rubber 9 on the central pivot pin 5 linking the two limbs 3A, 3B.

Figure 4 shows details of the rubber isolation bush. This WO 95/09757 PCT/GB94/02136 4 rubber 9 will also assist in centralising the system during manufacture and provide a seal at 30 in Figure 4.

The two crosses 4A, 4B can incorporate built-in seals.

During vehicle impact, the limbs 3A, 3B move or collapse into a closed position where the sides of limbs 3A, 3B contact one another (Figure The present coupling 10 can accommodate to 25mm of movement from an open position to a closed position. The coupling 10 can also accommodate minor differences in the lengths of the steering rack 20 pinion shaft and the lower shaft 23 due to manufacturing tolerances.

The shaft coupling 10 operates in an operating position wherein the limbs 3A, 3B are not co-axial, i.e. an angle less than 180 degrees.

Claims

1. A shaft coupling (10) comprising two universal joints (1, 2) and a torque transmitting means for pivotally connecting the two universal joints and for traismitting torque from one universal joint to the other universal joint, characterised in that the torque transmitting means includes a single central pivot pin through which torque from one universal joint is transmitted to the other universal joint.

2. A shaft coupling according to claim 1, comprising a first yoke wherein the universal joints comprise a first cross member (4A) pivotally connected to the first yoke a second yoke and a second cross member (4B) pivotally connected to the second yoke there being a single pivotable elbow member having two limbs (3A, 3B) pivotally connected through said single, central pivot pin each cross member being pivotally connected to a respective one of the pivotable elbow member limbs (3A, 3B).

3. A shaft coupling according to claim 2, further comprising means for inhibiting vibration transmission from one limb to the othe.r limb.

4. A shaft coupling according to claim 3, wherein the means for inhibiting vibrat-on transmission includes a rubber bush about the central pivot pin. A shaft coupling according to claim 2, 3 or 4, wherein each limb of the pivotable elbow member is forked so as to embrace and engage two ends of a said respective cross member.

AMENDED SHFET 4.

6 A shaft coupling according to claim 2, 3, 4 or 5, wherein the limbs contact each other when the pivotable elbow member is pivoted from an open position to a closed position.

7. A shaft coupling acccrding to any one of claims 2 to 6, wherein the limbs pivot from an operating position to a closed position, the angle between the limbs in the operating position being less than 180 degrees and the angle between the limbs in the closed position being less than the operating position angle.

8. A shaft coupling according to any one of claims 2 to 7, wherein the pivot axis of the two limbs and the pivot axes (7A, 7B) of the cross members (4A, 4B) of the elbow member (3) are parallel to one another.

9. A vehicle steering column (15) incorporating a shaft coupling (10) according to any one of the preceding claims and comprising an upper shaft (20) and a lower shaft the universal joints of said shaft coupling being coupled to the upper shaft and t4le lower shaft respectively. AMENDED SHEET